Ideal scan resolution?

[Poztron]

I don't know if this is the best sub-category to post this at, but I wanted to share some of my recent thinking about the great scans shared here. It seems like, especially with things like the JVJ project, many of the comics being scanned are getting a "once in a lifetime" chance to be archived. If that's so -- and we are trying to outrace the browning of newsprint some 60 years old -- then it suggests to me that we ought to try to scan the comics for the highest resolution practical at this point in the evolution of digital archiving.

What I gleaned from FAQs here was to do an initial scan at 300 dpi and only later reduce that tif to a resized jpeg with a 1024 pixel width. For most scanned comics I've done, that seems to have resulted in .cbrs or cbzs that are roughly 24 megs in size. With today's hard drives, that is a drop in the bucket.

(My ultimate concern is that these precious and perishable comics will disintegrate before we can archive high-resolution scans of them. 150 or 300 dpi may seems like sufficient at present, but I can only imagine that 5 or 10 years from now that level of resolution will seem like...oh, dot-matrix printouts  seem to us now. 

[srca1941]

150, yes. I think they're already past their prime. 300? Personally, I think 300 works just fine for archival purposes. It's print resolution, and we're talking about line drawings and simple color screens, not complex photographs. I've done multiple comparisons over the years where I've taken 300dpi scans, upconverted them to 600, and compared them with 600dpi scans of the same page, done at the same time, and found no discernable difference. This was with the intent of restoring those pages to black and white line art. There was no thickening of lines or jagging of edges. Color screens were likewise the same. Fine lines were no clearer/sharper at native 600 than in an upconverted 300.

Perhaps there is some difference on the ultra fine line work of Lou Fine, Reed Crandall, etc., but even then, I've found it hard to spot differences in quality with uncompressed scans. In my opinion, for all intents and purposes, 300dpi is a perfectly acceptable long-term resolution. In the interest of space, the files I upload here have been downconverted to 150 and compressed, but my master files are 300dpi, uncompressed JPGs.

-Eric

[Geo (RIP)]

I've been scanning at 300 ppi for a couple of years now, (before when I started scanning I did them at 150 ppi). I save the final jpg at around 950 kb for the cover and around 550 kb for the inside pages, so the book weights in around 21-25 megs. My first 300 ppi books ended at around 27-29 megs. And I use the 1280 width as a standard. As Eric has stated the fine art line work of a few artist does seem to show up better at 300 ppi, (Lou Fine, Reed Crandall, Al Williamson and Everett Raymond Kinstler are a few I can think of off the top of my head). With HD space so inexpensive, size doesn't matter as much as it did a few years ago, (a 2 TB drive are just a little over $100 now). We do have some here that are scanning at 600 ppi, (the Phantom Lady series comes to mind as one). A few other scanner have stated they are scanning that high to archive their raw scans.

And Poz you are right about the once in a life time on the JVJ books, we should do the best we can on them as it will be the only chance we get. When I do a JVJ book I try to make it look as it did when it came off the shelf, spin-rack, etc because of this, I just take the extra time with them, but that's just me, I'm sure others JVJ scanners are doing the same thing.

Geo

[Roygbiv666]

Not knowing anything about scanning, at approximately what dpi/ppi does a scan need to be that, if printed out on a high quality printer, would look the same to the naked eye as the original comic page? Around 300 dpi? is that how that level was originally set?

What are the main reasons for not going higher? Do most downloaders have usage limits on their internet service, or are they using really old dial-up, or something else? I just upgraded from the absolute cheapest ISP plan to the next cheapest, and a 25 Mb book downloads in seconds.

[narfstar]

The higher the ppi the longer it takes to scan. And we do still those on dialup or limited connection or bandwidth limits. I believe Yoc has bandwidth limits.

[Yoc]

Yeah, my ISP does set limits which I thought was the norm out there today.
As for me, scanning at higher resolutions was brutally slow.  Even at 150dpi it was a minute or two per page and at 300dpi I was nearly falling asleep waiting!  (half joke).  Now it might have been my scanner (HP Scanjet4370) or the very old PC I was using (P4 1.7ghz) but I just couldn't take the slow speeds and stuck with 150dpi while I was still scanning.
A better scanner and machine might easily handle the higher resolution.
A 68pg book at 300dpi would be a pretty large file.  We've been hosting mostly books in the 20-80mb range with some exceptions and haven't had any problems.  I think if the book is rare enough and the artwork exceptional it's certainly worth a higher resolution scan and would encourage scanners to do so if they are willing.

-Yoc

[Roygbiv666]

Yeah, my ISP does set limits which I thought was the norm out there today.
As for me, scanning at higher resolutions was brutally slow.  Even at 150dpi it was a minute or two per page and at 300dpi I was nearly falling asleep waiting!  (half joke).  Now it might have been my scanner (HP Scanjet4370) or the very old PC I was using (P4 1.7ghz) but I just couldn't take the slow speeds and stuck with 150dpi while I was still scanning.
A better scanner and machine might easily handle the higher resolution.
A 68pg book at 300dpi would be a pretty large file.  We've been hosting mostly books in the 20-80mb range with some exceptions and haven't had any problems.  I think if the book is rare enough and the artwork exceptional it's certainly worth a higher resolution scan and would encourage scanners to do so if they are willing.

-Yoc

You're in Ontario, aren't you? Yeah, I'm using Rogers, and their rate plans do have usage limits. I just upgraded from "Ultra-Lite", which is 2 Gb upload/download at $27.99/month, to "Lite" which is 15 Gb for $35.99/mo. I don't really do much except the occasional comic, music via iTunes, YouTube, or tvshack.cc, but I was going over the 2 Gb a little most months, so I upgraded.

If anyone is interested by way of comparison with wherever you live, these are the rate we pay in the Toronto area:
http://www.rogers.com/web/link/hispeedBrowseFlowDefaultPlans